1. Field of the Invention
The invention relates to heat pumps and method and refers more specifically to an earth type heat pump and method of operation thereof wherein vertical heat pickup tubes are provided in the earth operable in conjunction with heat transfer structure to passively provide heat from the earth to the heat pump, which earth type heat pump may be assisted with a solar heating system for heating heater tubes by means of a solar collector, which heater tubes are positioned vertically adjacent the heat pickup tubes and/or assisted by structure for and the step of adding moisture to the earth around the tubes.
2. Description of the Prior Art
In the past, earth type heat pumps have historically been connected with long lengths of tubing embedded in trenches extending horizontally at depths of approximately six feet. When such heat transfer tubes have been used with direct expansion in the earth, excessive pressure drop and return of oil to the compressor have been system problems. A fraction of a pound of pressure drop in such system results in a great decrease in capacity of the heat pump compressor. Also with such systems it has usually been necessary to manifold the pipes in the earth which is likely to result in oil being trapped due to lack of velocity and not being returned to the heat pump, resulting in burned out compressors. Another alternative in earth type heat pumps has been to use the horizontal trenches with a hydronic fluid circulated through the horizontal pipes and through a heat exchanger. Such structure eliminates the problem of oil return. However, such system still utulize considerable energy in circulating the hydronic fluid and require a considerable surface area to be excavated for the placement of the heat pickup tubes in the earth.